The present invention relates generally to axial flow rotary combines for harvesting and treating crop material and particularly to a feed rotor for the separator of such a machine.
It is well known that in a combine having an axial flow rotary separator and particularly one with a fore-and-aft axis that the transfer of harvested crop material from a gatherer to the first crop treating portion of the separator (usually a threshing portion) is difficult to achieve efficiently involving, as it does generally, a rapid change of speed and direction of the material. Typically, crop material is delivered to the separator by a feeder house conveyor upwardly and rearwardly in a fore-and-aft direction at relatively low speed and the separator rotor is provided with a special forward feed rotor portion for receiving the material and transferring it rearwardly and spirally into the threshing portion. In a feeding system, the material is generally confined within housings or casings including typically, first that of the feeder house and subsequently a transition housing (between feeder house and separator), a separator infeed housing and finally the casing (with grates) of the separator proper.
The difficulties of achieving an efficient transfer of crop material from the gatherer to the separator in axial flow combines are indicated by the many patents directed to this area issuing in recent years. Attempts to provide an efficient separator feeding system have included: variations in the positional relationships of feeder house conveyor discharge and rotor, including undershot and end-feeding arrangements; variations in the shape of the transitional housing between feeder house and infeed housing of the separator; and variations in the form of the separator rotor infeed portion itself. Also, as described in co-pending U.S. patent application Ser. No. 889,626, also assigned to the assignee of the present invention, a special rotor transition portion may be provided between rotor feed and threshing portions to better condition the incoming crop material for reception by the threshing portion.
Typically, feed rotors have consisted of a core on which are mounted sets of two or more generally helical flights and variations have included forwardly inclining such flights with respect to direction of rotation and forming the forward end of such blades to have a scooping effect to make the acceptance of the crop material by the rotor more positive. A variety of combinations of helical flighting and cylindrical and frusto-conical forms for the core of the feed rotor have also been proposed. However, typically in these variations, a continuous flighting form is retained, uninterrupted over the length of the rotor feed portion and resulting in an abrupt shearing effect and very rapid acceleration of the material as it leaves the feeder house conveyor and encounters the feed rotor flighting. The result is extra grain damage and chaff generation and undesirably high torque peaks in the separator and feeder house drive systems. These effects are magnified when the feed rotor flighting is of extended pitch or inclined in the direction of rotation. Such flighting offers a wall to the crop material and no direct diversion outwards into a radial mat as is desirable to prepare it for reception by the threshing section. Further and typically, there is slippage between the crop material and the feed rotor (the average rotational velocity of the crop material never reaches that of the rotor) and circumferential friction between crop material and the sharp edges of the rotor flighting as the material rides over those edges increases power consumption. The power consumption of the feeder house may also be increased by the "chopping" action of an aggressive feed rotor which may actually offer a fluctuating impedance to the flow of material from the feeder house.